This invention relates to the measurement of temperatures, and, more particularly, to determining surface temperatures.
The temperature to which an article is heated during processing is often a critical factor in the final outcome and success of the processing. For example, when microelectronic devices are prepared, there are often numerous heat treatments for annealing, controlled interdiffusion, and other reasons. The properties of the final devices often depend on the temperatures reached during the various heat treatments. Great care is ordinarily taken to control the heating equipment so that the desired temperature is reached. However, the actual temperature reached is not known with certainty unless it is actually measured, because there may be equipment malfunctions, internal variations within a heated region, etc.
Temperatures are measured by a wide variety of techniques. Many of the most familiar techniques such as thermometers, thermocouples, pyrometers, temperature strips, and temperature marking crayons are not suitable for measuring the processing temperature reached in microelectronic device processing. In some instances the devices are so small that conventional measuring devices are of too gross a size to measure the local temperature of the processed device. In other instances the surface of the device is preferentially heated, as by plasma heating. A conventional temperature measurement method is not well suited for measuring the local surface temperature of the device heated in this manner, because the surface is preferentially heated. Temperature marking crayons may contaminate the surface of a sensitive semiconductor device, and therefore cannot be used in such applications.
There is a need for an improved approach to measuring the temperature of articles during processing, and particularly the surface temperatures achieved by surface-heating techniques. The present invention fulfills this need, and further provides related advantages.